用区间有限元计算桥梁结构荷载组合效应

不确定的桥梁结构荷载 ,可以用上、下限的区间来表示 ,用区间有限元 (FEM)方法可以求得结构位移和内力响应的包络界限 .用线弹性梁单元对实际桥梁结构进行离散化 ,并用确定的区间值表示不确定的荷载向量 ,根据区间代数原理和线性有限元程序求解响应量的界限 ,从而得到结构响应量不确定性的界限 .用该方法计算桥梁结构设计中的荷载工况组合效应 ,算例表明该方法具有使用简便、计算量小的特点 ,适合实际桥梁结构设计的荷载组合计算

Interval FEM used in the calculation of bridge and structural response under combinatorial loads

The loading uncertainties of bridge and structure may be expressed by the upper and lower boundaries of an interval. The interval Finite Element Method (FEM) is used to obtain the conservative bounds for the displacement and force response quantities. The linear elastic beam elements are applied in the discretization of a real bridge. The bounded intervals are used in expressing the load vector with unertainties. The conservative bounds for the response quantities are determined by the theory of interval algebra and linear elastic programming. Then, the conservative bounds for the rsponse can be obtained. The proposed formulation is applied to the practical design of bridge and structure loading combinations. The results of an example indicate that the method used here is convenient and simple. This method also has snall calculation work and is suitable to calculate the loading combinations of bridges and structures in the practical design.